Chapter 23

Question 1

what does safety involve?

Answer 1

safety googles, a laboratory coat or apron and closed-toed shoes
- Gloves are appropriate sometimes

Question 2

what should all labs have

Answer 2

have an eyewash station, shower station, fire extinguisher, emergency exit

Question 3

what is accuracy

Answer 3

a measurement giving the actual value for the sample with a limited deviation

Question 4

what is precision

Answer 4

the repeatability of a set of measurements on the same sample

Question 5

why is glass preferred for chemical application

Answer 5

bc of its strength, inertness, transparency, and heat resistance

Question 6

what are Test tubes, beakers, and Erlenmeyer flasks

Answer 6

used for many of the routine mixing and reaction tasks of the lab

Question 7

what are test tubes

Answer 7

are relatively small and allow a large number of samples to be arrayed in a task in a rack for easy processing

Question 8

what are beakers

Answer 8

wide mouthed cylinders with a lip to allow pouring

-Flat bottom so they can stand on their own

Question 9

what are Erlenmeyer flasks

Answer 9

tapered and therefore minimize accidental spills

• The neck of the flask allow sit to be clamped in place either on the laboratory bench or above it on a sand
• Some can be sealed with rubber, cork, or ground glass stoppers
• Flat bottom so they can stand on their own

Question 10

what are round-bottom flasks

Answer 10

used for reaction, heating or vacuum applications

Question 11

what does spherical shape and wall thickness of the round-bottom flask provide

Answer 11

-extra strength and fit into a heating mantle and the narrow neck allows the flask to be clamped into place

Question 12

what kind of experiments round-bottom flasks used for

Answer 12

experiments that require that require distillation to isolate product

Question 13

what is a retort for round-bottom flasks

Answer 13

a round vacuum flask with a long neck that extends to the side
- It is used for distillation and must be placed on a ring stand or heating mantle

Question 14

what is a Extraction flask (separatory funnel)

Answer 14

a teardrop-shaped flask with a ground glass stopper at the top and a stopcock at the bottom

Question 15

how are Extraction flask (separatory funnel) used

Answer 15

• 2 different solvents are mixed by shaking the flasks, venting to prevent breakage and are then allowed to separate by density, the lower layer is removed by draining through the stopcock
• often used to separate polar mc from non-polar mc, the 2 liquids in the separatory funnel must be immiscible to complete the separation

Question 16

can a Extraction flask stand on its own

Answer 16

-placed in a ring stand bc cannot stand on its own

Question 17

which pipets are made of glass and which are made of plastic

Answer 17

pastic: transfer pipet
glass: pasture pipet

Question 18

small bottles

Answer 18

vials

Question 19

cylindrical containers with wide openings that may be sealed

Answer 19

jars

Question 20

used to contain vacuums

Answer 20

bell jars

Question 21

shallow glass plates used as evaporating surfaces or to cover beakers

Answer 21

watch glass

Question 22

___glassware is used for any lab measurement that requires accuracy and precision

Answer 22

calibrated

Question 23

what is a graduated cylinder

Answer 23

a tall, narrow tube with volume markings increasing from bottom to top and a lip at the top for pouring

Question 24

when do you see a concave meniscus

Answer 24

if the liquid is attracted to the side of the cylinder

Question 25

when do you see a convex meniscus

Answer 25

mc of the liquid is more attracted to each other than the cylinder

Question 26

what are burets and pipets used for

Answer 26

deliver exact volumes of liquids

Question 27

what is a buret

Answer 27

a long tube that is clamped in place vertically with a stopcock at the bottom
- used to make solutions and to perform titrations

Question 28

what is volumetric pipet

Answer 28

have a large bulb in the middle of the tube and deliver a single established volume of liquid with great accuracy and precision

Question 29

what is graduated pipet

Answer 29

hand-held and controlled by a pipet bulb that maintains a slight vacuum at the top of the pipet

Question 30

what is a volumetric flask

Answer 30

is used to make solutions that require a specific volume of liquid

Question 31

what is a pH meter and how does it work

Answer 31

consists of a glass probe and an electronic meter
-measures the acidity or basicity of a solution by comparing the voltage ( electrical potential) produced by the solution compared to the voltage of a known standard solution and uses the difference in voltage ( the potential difference) between them to calculate the pH

Question 32

what colour is litmus paper for acid, basic and neutral conditions

Answer 32

• red under acidic conditions ( <4.5)
• blue under basic conditions ( >8.3)
• purple neutral

Question 33

what is calorimetry

Answer 33

a way for chemists to measure the energy content of a substance

Question 34

how does a bomb calorimeter work

Answer 34

1) the fuel (sample being measured) is ignited, heating up the surrounding air
2) the air heats surrounding water and using the specific heat of the water it is possible to measure the heat content and thereby calculate the internal energy of the sample